Biologists are studying why a baby's instinctive behavior -- specifically, stuffing dirt into her mouth -- would be in fact beneficial. They propose a 'hygiene hypothesis," eating dirt and the billions of microbes and, yes, worms inside that dirt may sicken the child (and parent) in the short term, but will reduce the chance of developing immune-related illnesses in the long run.
According to immunologist Mary Ruebush, children raised in a hyper-clean environment are not exposed to the organisms that help them develop appropriate immune circuits. Research suggests that the increase in immune system disorders (e.g., asthma, allergies, multiple sclerosis, Type I diabetes, and inflammatory bowel disease) in the US may be due to our restrictions on the environment and behavior of our children.
Dr. David Elliott of the University of Iowa cites specific evidence in developing countries; for example, he claims that the eradication of worms in some villages in Gambia have led to an increase in children's skin allergies.
Obviously, dirtiness is not a desirable outcome. But too much cleanliness is harmful, too. Professor Ruebrush suggests that we rue antibiotic products and stick with plain soap and water whenever our hands need washing. Dr. Joel Weinstock of Tufts Medical Center goes even further: “Children should be allowed to go barefoot in the dirt, play in the dirt, and not have to wash their hands when they come in to eat." He also suggests that kids have two dogs and a cat, which will expose them to intestinal worms that can promote a healthy immune system.
Read the NYT article here.
9/17/09 Update:
A man infects himself with hookworm to cure his asthma and hayfever. Listen to his account on Radiolab (his story begins at ~32 minute mark in the show). This cute little bloodsucker can cure your asthma.
